This invention relates in general to speed reducer constructions and in particular to a new and useful power drive speed reducer particularly adapted for use with cam operated mechanisms requiring accurate speed control.
A fundamental requirement for a well designed speed reducer for the operation of cam control devices for automatic mechanisms is that it rotate at a constant rotational velocity in order to preserve the parameters which are inherently necessary for optimum dynamics in the movement of the cams and the controlled linkages. Of course with such devices the torque loads will vary considerably and there is a danger that the cam and associated linkages will run ahead of the driving means unless the driving mechanism is arranged so that it may be accurately and positively connected to the associated cam elements which are driven thereby. In the known devices the speed reducers undergo considerable slowdowns for positive torque build up and they are subject to a speed up when the torque is removed or reversed as is the case with the operation of a spring biased cam. In most cases when spring biasing devices are employed there is considerable weight acting on the fore portion of the cam. The presence of excessive backlash in the gearing is apt to cause jumping ahead of the mechanism. All of these conditions contribute to a non-uniform rotation of the mechanism cams causing unacceptable component output motions in many instances.